The present invention relates to an actuator having a linear motor and a table device provided with the actuator.
Generally, a linear motor is constituted by a stationary shaft such as a permanent magnet, etc. and a needle such as a coil, etc. Also, since linear motors do not normally include a guide mechanism for a moving direction, it is necessary to provide a linear guide (guide mechanism) for straight or curved advancement in a direction, in which a needle moves, in the case where a linear motor is incorporated in a table, etc. to be used. That is, a linear guide serving as a guide mechanism and a linear motor are separately provided. There are proposed various actuators, in which such a linear motor is incorporated in a table, etc.
However, since it is required that a linear guide and a linear motor in the actuators described above be provided separately in a vertical direction as shown in, for example, FIGS. 23 and 24, the actuators are generally made large in size and encounter a difficulty in miniaturization. Also, moment in a heightwise direction is generated due to a distance H between centers of balls interposed between a linear guide block and a linear guide rail and a center of a linear motor, so that a needle, a table, and the like undergo postural change to be difficult to move with accuracy.
Also, even when a linear motor is arranged centrally between two linear guide blocks independent of the linear motor so as not to be influenced by moment, a width, over which guiding is effected, is increased in a direction of movement of a needle, a table, etc., so that designing of a narrow guide is not possible, straightness is bad, and movement with high accuracy is also difficult. In addition, as shown in FIGS. 23 and 24, with a linear guide, which makes use of, for example, static-pressure guides instead of a linear guide making use of balls, designing of a narrow guide is also difficult and movement with high accuracy is difficult.
In this manner, it is difficult to make miniaturization as a whole and designing of a narrow guide compatible with each other.